System-on-chip camera with integrated light sensor(s) and method of producing a system-on-chip camera

ABSTRACT

The system-on-chip camera comprises a semiconductor body with an integrated circuit, a sensor substrate, sensor elements arranged in the sensor substrate according to an array of pixels, a light sensor in the sensor substrate apart from the sensor elements, and a lens or an array of lenses on a surface of incidence. Filter elements, which may especially be interference filters for red, green or blue, are arranged between the sensor elements and the surface of incidence.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/309,226, filed Dec. 12, 2018, now allowed, which is anational stage entry of International Patent Application No.PCT/EP2017/064421, filed on May 29, 2020, and published as WO2020/245061 A1 on Jun. 13, 2017, which claims the benefit of priority ofEuropean Patent Application No. 16174805.8 filed on Jun. 16, 2016, allof which are incorporated by reference herein in their entireties.

BACKGROUND OF THE INVENTION

In a system on chip (SoC) all components of an electronic system ordevice are integrated into or onto a single chip.

U.S. Pat. No. 7,875,947 B2 discloses color filters formed of alternatelystacked inorganic materials of different refractive indices like SiO₂,SiON, SiN or Si.

U.S. Pat. No. 8,284,291 B2 discloses an optical lens assembly comprisinga lens with a concave surface on the side of the image, the surfacehaving at least one inflection point.

U.S. Pat. No. 8,964,062 B1 discloses a camera of a computing device withan integrated ambient light sensor in the camera module. Amicroprocessor analyzes data obtained from the sensor.

U.S. Pat. No. 9,232,150 B2 discloses a system for calculating an ambientlight estimate using an image sensor and a matrix of grid elements eachcomprised of multiple adjacent pixels.

U.S. 2014/0022650 A1 discloses an optical unit comprising two lensesarranged between two substrates for use in image processing units likecameras.

U.S. 2016/0006913 A1 discloses an optical apparatus comprising asemiconductor substrate with an image sensor and an ambient light sensorand/or proximity sensor, and an optics substrate with a lens element.

SUMMARY OF THE INVENTION

The system-on-chip camera comprises a sensor substrate comprisingsemiconductor material, sensor elements arranged in the sensor substrateaccording to an array of pixels, a light sensor in the sensor substrateapart from the sensor elements, and a surface of incidence above thesensor elements and the light sensor. The sensor substrate is connectedto a semiconductor body comprising an integrated circuit and is arrangedbetween the semiconductor body and the surface of incidence. Each of thesensor elements is provided with a further component arranged betweenthe sensor element and the surface of incidence, the further componentbeing a filter element or a stack of further sensor elements.

In an embodiment of the system-on-chip camera, a front dielectric layeris arranged between the sensor substrate and the surface of incidence,and each of the further components is a filter element arranged in thefront dielectric layer.

Each of the filter elements may especially be a band-pass filter foreither red, green or blue light.

In a further embodiment, metal spacers are laterally arranged at thefilter elements or further sensor elements.

In a further embodiment, a further band-pass filter for either red,green or blue light is arranged as a filter layer between the lightsensor and the surface of incidence.

In a further embodiment, each of the further components is a stack offurther sensor elements, the sensor element and the further sensorelements being arranged at different distances from the surface ofincidence.

In a further embodiment, a lens or an array of lenses is formed by anoxide of semiconductor material arranged on the surface of incidence.

In a further embodiment, a molding material covers the lens or array oflenses, and a diffusor is formed above the light sensor by a modifiedregion of the molding material.

A further embodiment comprises a metallization layer between thesemiconductor body and the sensor substrate, a contact pad, a via holein the semiconductor body, and a metallization in the via hole. Thesemiconductor body is between the metallization layer and the contactpad. The metallization in the via hole electrically connects themetallization layer and the contact pad.

A further embodiment comprises a metallization layer between thesemiconductor body and the sensor substrate, an optical component abovethe surface of incidence and a through-substrate interconnectionelectrically connecting the metallization layer and the opticalcomponent.

A further embodiment comprises an optical via penetrating thesemiconductor body and an optical component opposite the optical via ona side facing away from the sensor substrate. In further embodiments thelight sensor is a sensor selected from the group consisting of ambientlight sensor, color sensor, hyperspectral sensor with multiple pixels orbands, infrared sensor and UV sensor.

A further embodiment comprises a proximity sensor, a gesture sensor or atime-of-flight sensor including a light source.

In a further embodiment the light sensor comprises an array of lightsensors serving as a further camera.

In one aspect the method of producing a system-on-chip camera comprisesproviding a semiconductor body with an integrated circuit, providing asensor substrate with sensor elements, which are arranged according toan array of pixels, and with a light sensor apart from the sensorelements, fastening the sensor substrate to the semiconductor body, andforming at least one plurality of filter elements. Each plurality offilter elements is formed by arranging a filter layer on a planarsurface above the sensor substrate, applying a mask on the filter layer,the mask covering areas provided for the filter elements, structuringthe filter layer using the mask, and planarizing the surface.

In particular three pluralities of filter elements may be provided forthe system-on-chip camera by arranging a first filter layer on thesensor substrate, applying a first mask on the first filter layer, thefirst mask covering areas provided for filter elements of a first type,structuring, especially etching, the first filter layer using the firstmask, planarizing the surface, arranging a second filter layer on theplanarized surface, applying a second mask on the second filter layer,the second mask covering areas provided for filter elements of a secondtype, structuring, especially etching, the second filter layer using thesecond mask, planarizing the surface, arranging a third filter layer onthe planarized surface, applying a third mask on the third filter layer,the third mask covering areas provided for filter elements of a thirdtype, structuring, especially etching, the third filter layer using thethird mask, and planarizing the surface.

In a variant of this method, a UV IR blocking filter layer is arrangedon the planarized surface after the last filter layer is etched. Afurther mask is applied on the UV IR blocking filter layer, the UV IRblocking filter layer is etched using the further mask, and the surfaceis planarized.

In a further variant of this method, a lens layer is arranged above thesensor substrate, and a transfer mask having the shape of a lens or anarray of lenses, is applied on the lens layer. A lens or an array oflenses is formed by transferring the shape of the transfer mask to thelens layer.

In a further aspect the method of producing a system-on-chip cameracomprises providing a semiconductor body with an integrated circuit,providing a sensor substrate with sensor elements, which are arrangedaccording to an array of pixels, and with a light sensor apart from thesensor elements, fastening the sensor substrate to the semiconductorbody, and arranging a lens or an array of lenses above the sensorsubstrate. The lens or array of lenses may be formed by arranging a lenslayer above the sensor substrate, applying a transfer mask on the lenslayer, the transfer mask having a shape of a lens or an array of lenses,and forming a lens or an array of lenses by transferring the shape ofthe transfer mask to the lens layer.

In a further variant of the method, a molding material is applied tocover the lens or array of lenses, and a diffusor is formed above thelight sensor by modifying the molding material in a region above thelight sensor.

In a further variant of the method, metal spacers are formed at thefilter elements by etching trenches in the planarized surface andfilling the trenches with a metal.

The following is a detailed description of embodiments of thesystem-on-chip camera with integrated light sensor and the method ofproducing a system-on-chip camera in conjunction with the appendedfigures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section of a system-on-chip camera with filters, lightsensor, vias and molding material.

FIG. 2 is a cross section according to FIG. 1 for a system-on-chipcamera with a different filter.

FIG. 3 is a cross section of a system-on-chip camera with filters, lightsensor, optical via and molding material.

FIG. 4 is a cross section of a system-on-chip camera with sensor stacks,light sensor, vias and molding material.

FIG. 5 is a cross section of a system-on-chip camera with sensor stacks,light sensor, optical via and molding material.

FIG. 6 is a cross section of a further system-on-chip camera withfilters, light sensor, vias and molding material.

FIG. 7 is a cross section of a system-on-chip camera with filters, lightsensor and vias.

FIG. 8 is a cross section of a further system-on-chip camera withfilters, light sensor and vias.

FIG. 9 is a cross section according to FIG. 8 for a system-on-chipcamera with a different filter.

FIG. 10 is a cross section of a system-on-chip camera with sensorstacks, light sensor and vias.

FIG. 11 is a cross section according to FIG. 10 for a system-on-chipcamera with a different filter.

FIG. 12 is a top view of an arrangement of sensors.

FIG. 13 is a cross section of an intermediate product after a firstfilter layer is applied.

FIG. 14 is a cross section according to FIG. 13 after the first filterlayer is structured and the surface is planarized.

FIG. 15 is a cross section according to FIG. 14 after a mask is appliedon the planarized surface.

FIG. 16 is a cross section according to FIG. 15 after trenches areetched in the planarized surface.

FIG. 17 is a cross section according to FIG. 16 after the trenches arefilled.

FIG. 18 is a cross section according to FIG. 17 after a second filterlayer is applied.

FIG. 19 is a cross section according to FIG. 18 after the second filterlayer is structured and the surface is planarized.

FIG. 20 is a cross section according to FIG. 19 after a third filterlayer is applied.

FIG. 21 is a cross section according to FIG. 20 after the third filterlayer is structured and the surface is planarized.

FIG. 22 is a cross section according to FIG. 21 after a blocking filterlayer is applied.

FIG. 23 is a cross section according to FIG. 22 after a further mask isapplied.

FIG. 24 is a cross section according to FIG. 23 after a lens layer and atransfer mask are applied.

FIG. 25 is a cross section according to FIG. 24 after lenses are formed.

FIG. 26 is a cross section according to FIG. 25 after via holes areformed in the semiconductor body.

FIG. 27 is a cross section according to FIG. 26 after electrical andoptical vias are formed.

DETAILED DESCRIPTION

FIG. 1 is a cross section of a system-on-chip camera with an integratedlight sensor. A semiconductor body 1 is fastened to a sensor substrate 2comprising semiconductor material, which may be of the same kind as thesemiconductor material of the semiconductor body 1, in particularsilicon, for instance. Sensor elements 3 are arranged in the sensorsubstrate 2 according to an array of pixels, and at least one lightsensor 4 is arranged in the sensor substrate 2 apart from the sensorelements 3. FIG. 1 shows one light sensor 4 by way of example, but twoor more light sensors 4 may be integrated. The sensor elements 3 may beseparated from one another and from the sensor substrate 2 by deeptrench isolations 16, for instance. The light sensor 4 may be separatedfrom the sensor substrate 2 by deep trench isolations 16, for instance.

A front dielectric layer 5 may be present on the front side of thesensor substrate 2 facing away from the semiconductor body 1. Anintermediate dielectric layer 6 may be arranged between thesemiconductor body 1 and the sensor substrate 2. The intermediatedielectric layer 6 may comprise a layer portion that is applied to thesemiconductor body 1 and a further layer portion that is applied to thesensor substrate 2 before the sensor substrate 2 is fastened to thesemiconductor body 1. The boundary between these layer portions isindicated in FIG. 1 by a horizontal broken line. The layer portions mayserve to fasten the sensor substrate 2 to the semiconductor body 1 bybonding. A rear dielectric layer 7 may be present on the side of thesemiconductor body 1 facing away from the sensor substrate 2.

The intermediate dielectric layer 6 may include a wiring comprisingstructured metallization layers 8 and vertical interconnections 9. Thewiring may especially be connected to the array of sensor elements 3,the light sensor 4 and/or components of an integrated circuit 40 in thesemiconductor body 1. Details of the integrated circuit 40 are notessential, and the integrated circuit 40 is therefore only schematicallyindicated in FIG. 1 by doped wells. The integrated circuit 40 may inparticular be a CMOS circuit, for instance.

In the system-on-chip camera according to FIG. 1, filter elements 11,12, 13 are arranged above the sensor elements 3. It may be suitable toarrange filter elements of the same type of filter on the same levelabove the sensor elements 3. A filter layer 10 may be arranged above thelight sensor 4. The filter layer 10 may be a band-pass filter for eitherred, green or blue light. Filter elements of a first type 11 may bearranged in a first layer portion of the front dielectric layer 5,filter elements of a second type 12 may be arranged in a second layerportion of the front dielectric layer 5, and filter elements of a thirdtype 13 may be arranged in a third layer portion of the front dielectriclayer 5. The filter elements of the first type 11 may be band-passfilters for red, the filter elements of the second type 12 may beband-pass filters for green, and the filter elements of the third type13 may be band-pass filters for blue, for example. The order of thelevels on which filter elements of the same type, especially red, greenor blue filters, are arranged is arbitrary. The optional filter layer 10may be on the same level with the filter elements of any of the types11, 12, 13. The band-pass filters may be formed by interference filters,for instance.

The number of levels on which filter elements are arranged may differfrom the system-on-chip camera shown in FIG. 1 and may especially belarger. Further types of filters may be arranged in the system-on-chipcamera, in particular filters that are provided to protect theintegrated circuit from radiation.

A UV IR blocking filter 14 is optionally arranged above the filterelements 11, 12, 13. The UV IR blocking filter 14, which preventsultraviolet and infrared radiation from reaching the sensor elements 3,may be an interference filter comprising a sequence of layers, which areschematically indicated in FIG. 1. The UV IR blocking filter 14 may forman entire layer, or it may be recessed above the light sensor 4, asshown in FIG. 1 by way of example. Another type of filter may beemployed instead of the UV IR blocking filter 14, in particular a filterthat blocks either ultraviolet radiation or infrared radiation,according to the intended application.

The light sensor 4 can be an ambient light sensor, a color sensor withthree pixels or bands (RGB or XYZ), for instance, a hyperspectral sensor(on-chip spectrometer) with multiple pixels or bands (e. g. more than 3and up to 256), an IR sensor above which the UV IR blocking layer 14 isopened or an UV sensor above which the UV IR blocking layer 14 isopened. Applications include any system-on-chip combining a camera withsuch sensors. Further to the light sensor 4, the system-on-chip cameramay comprise a proximity sensor, a gesture sensor or a time-of-flightsensor including a light source, especially for emitting and detectingIR radiation, and optical barriers. The light sensor 4 may have multiplepixels forming an array serving as a further camera.

A surface of incidence 30 is provided on a side of the sensor substrate2 facing away from the semiconductor body 1, where radiation is allowedto enter the system-on-chip camera in the direction indicated in FIG. 1by the arrows pointing downwards. A lens 15 or an array of lenses 15 isapplied on the surface of incidence 30 above the array of sensorelements 3 and may especially be formed in a layer of transparent orsemitransparent material, which may be an oxide of the semiconductormaterial of the sensor substrate 2, in particular SiO₂, for instance.The lens 15 or array of lenses 15 may also be arranged above the lightsensor 4 as shown in FIG. 1 by way of example.

Contact pads 17 or a redistribution layer may be arranged on the rearside of the semiconductor body 1, facing away from the sensor substrate2. Solder balls 18 may be arranged on at least some of the contact pads17 for external electric connection. A passivation 46, which does notcompletely cover the contact pads 17, may also be applied on the rearside.

A via hole 19 or a plurality of via holes 19 may be present in thesemiconductor body 1. An electric interconnection between a contact pad17 and a metallization layer 8 embedded in the intermediate dielectriclayer 6 can be formed by a metallization 21, which is arranged in one ofthe via holes 19. A dielectric interlayer 20 optionally insulates thesemiconductor body 1 from the metallization 21 to prevent a shortcircuit through the semiconductor body 1.

FIG. 1 shows optional metal spacers 22, which can be arranged at lateralsurfaces of the filter layer 10 and the filter elements 11, 12, 13 toform apertures limiting the solid angle of incidence. The metal spacers22 may comprise TiN or W, for instance, and may be formed by chemicalvapor deposition and subsequent etching, for instance.

FIG. 1 also shows an arrangement of a further optical component 24. Inthis example, the optical component 24 is a vertical-cavitysurface-emitting laser (VCSEL), but other optical components may beprovided in similar fashion. Further contact pads 25 andthrough-substrate vias 29 may serve as electric connections betweenterminals of the optical component 24 and metallization layers 8 of thewiring. The direction of light emission from the optical component 24 isindicated in FIG. 1 by arrows pointing upwards.

The lens 15 or array of lenses 15 may be covered by a molding material36, which is sufficiently transparent or at least semitransparent forradiation within a desired range of wavelengths. An optical isolation37, which is essentially opaque for the relevant range of wavelengths,in particular for radiation emitted by the optical component 24, may beformed in the molding material 36 to provide an aperture. A diffusor 38can also be formed in the molding material 36, in particular above thelight sensor 4, by a regional modification of the molding material 36,which is known per se. Such a diffusor 38 helps to eliminate shifts inthe characteristics of the filter layer 10 that are due to a dependencyof the filter characteristics on the angle of incidence of theradiation.

FIG. 2 is a cross section according to FIG. 1 for a furthersystem-on-chip camera with an integrated light sensor. The UV IRblocking filter 14 is recessed above the light sensor 4, and a furtherfilter 48 is arranged above the light sensor 4. The further filter 48may especially be an IR pass filter, which allows infrared radiation toreach the light sensor 4, and/or a UV blocking filter, which preventsultraviolet radiation from reaching the light sensor 4. The UV IRblocking filter 14 and the further filter 48 may be arranged on the samelevel, or one of these filters 14, 48 may be on a higher level than theother one.

FIG. 3 is a cross section of a further system-on-chip camera with anintegrated light sensor. Elements of the embodiment according to FIG. 3that are similar to corresponding elements of the embodiment accordingto FIG. 1 are designated with the same reference numerals. In theembodiment according to FIG. 3, the optical component 24 is arranged onthe rear side of the semiconductor body 1. An optical via 39, which maycomprise a sidewall insulation 47, is provided in the semiconductor body1 opposite the optical component 24. The sensor substrate 2 is recessedabove the optical component 24. If the optional UV IR blocking filter 14is present, it is also recessed above the optical component 24. Thus thedirection of the radiation emitted by the optical component 24 can bethe same as in the embodiment according to FIG. 1. The emitted radiationis indicated in FIG. 3 by the arrows pointing upwards.

FIG. 3 further shows an optical confinement 23 for the light sensor 4.The optical confinement 23 may be a layer surrounding the region that islocated above the light sensor 4 and may especially be a metal layer, inparticular TiN or W, for instance. The optical confinement 23 may beformed by etching a trench in the front dielectric layer 5 andoptionally in the sensor substrate 2, filling the trench with the metaland planarizing the surface. Such an optical confinement 23 may also beprovided in the embodiment according to FIG. 1 or FIG. 2. FIG. 3 showsthe filter layer 10 arranged on the level of the filter elements 13, byway of example. This level is higher than the level of the filter layer10 in the arrangements shown in FIGS. 1 and 2. Instead, the filter layer10 can be arranged on one of the lower levels of the filter elements 11or 12. A UV IR blocking filter 14 and/or a further filter 48 may bearranged above the light sensor 4 as in the embodiments according toFIG. 1 or 2.

FIG. 4 is a cross section of a further system-on-chip camera with anintegrated light sensor. Elements of the embodiment according to FIG. 4that are similar to corresponding elements of the embodiments accordingto FIG. 1 or 2 are designated with the same reference numerals. In theembodiment according to FIG. 4, further sensor elements 3′ are arrangedabove the sensor elements 3 instead of filter elements. The distances ofthe sensor elements 3 and further sensor elements 3′ from the surface ofincidence 30 vary in each of the stacks. As the depth of penetration oflight into silicon depends on the wavelength, the spectral sensitivitiesof the sensor element 3 and the further sensor elements 3′ of the samestack are all different from one another. A separate detection of red,green and blue light by individual sensor elements is thus feasiblewithout using filters. The further sensor elements 3′ may be providedwith metal spacers 22 similar to the metal spacers 22 of the filterelements 11, 12, 13 in the embodiment according to FIG. 1.

FIG. 5 is a cross section of a further system-on-chip camera with anintegrated light sensor. Elements of the embodiment according to FIG. 5that are similar to corresponding elements of the embodiment accordingto FIG. 3 are designated with the same reference numerals. Theembodiment according to FIG. 5 differs from the embodiment according toFIG. 3 in that, instead of filter elements, further sensor elements 3′are arranged above the sensor elements 3 as in the embodiment accordingto FIG. 4.

As in the system-on-chip cameras according to FIGS. 1 to 4, furthertypes of filters may be provided in the system-on-chip camera accordingto FIG. 5, in particular filters protecting the integrated circuit fromradiation.

FIG. 6 is a cross section of a further system-on-chip camera with anintegrated light sensor. Elements of the embodiment according to FIG. 6that are similar to corresponding elements of the embodiment accordingto FIG. 1 are designated with the same reference numerals. Theembodiment according to FIG. 6 is not provided with an optical component24. It comprises an optical confinement 23 as described above inconjunction with the embodiment according to FIG. 3 and a moldingmaterial 36 including a diffusor 38 as described above in conjunctionwith the embodiment according to FIG. 1. In the embodiment according toFIG. 6, the UV IR blocking filter 14 extends over the light sensor 4.The UV IR blocking filter 14 may instead be recessed as in theembodiments according to FIGS. 1 to 5. A further filter 48 may bearranged above the light filter 4 as in the embodiment according to FIG.2.

FIG. 7 is a cross section of a further system-on-chip camera with anintegrated light sensor. Elements of the embodiment according to FIG. 7that are similar to corresponding elements of the embodiment accordingto FIG. 6 are designated with the same reference numerals. Theembodiment according to FIG. 7 is not provided with a molding material.If the lens 15 or array of lenses 15 is formed in a lens layer 35,portions of the lens layer 35 may also remain in areas that are notoccupied by the lens 15 or array of lenses 15, as shown in FIG. 7. In afurther embodiment the lens 15 or array of lenses 15 may only bearranged above the array of sensor elements 3, but not above the lightsensor 4, while the other features are the same as in the embodimentaccording to FIG. 7. In the embodiment according to FIG. 7 a furtherfilter 48 is arranged above the light sensor 4, as in the embodimentsaccording to FIGS. 2 and 4.

FIG. 8 is a cross section of a further system-on-chip camera with anintegrated light sensor. Elements of the embodiment according to FIG. 8that are similar to corresponding elements of the embodiment accordingto FIG. 7 are designated with the same reference numerals. Theembodiment according to FIG. 8 is not provided with an opticalconfinement 23. The lens 15 or array of lenses 15 is arranged above thearray of sensor elements 3, but not above the light sensor 4.

FIG. 9 is a cross section of a further system-on-chip camera with anintegrated light sensor. Elements of the embodiment according to FIG. 9that are similar to corresponding elements of the embodiment accordingto FIG. 8 are designated with the same reference numerals. In thesystem-on-chip camera according to FIG. 9, the UV IR blocking filter 14is recessed above the light sensor 4, and a further filter 48 isarranged above the light sensor 4. The further filter 48 may especiallybe an IR pass filter, which allows infrared radiation to reach the lightsensor 4, and/or a UV blocking filter, which prevents ultravioletradiation from reaching the light sensor 4.

FIG. 10 is a cross section of a further system-on-chip camera with anintegrated light sensor. Elements of the embodiment according to FIG. 10that are similar to corresponding elements of the embodiment accordingto FIG. 8 are designated with the same reference numerals. Theembodiment according to FIG. 10 comprises an optical confinement 23 asdescribed above in conjunction with the embodiment according to FIG. 3.The array of sensor elements 3 is provided with further sensor elements3′ as in the embodiment according to FIG. 4.

FIG. 11 is a cross section of a further system-on-chip camera with anintegrated light sensor. Elements of the embodiment according to FIG. 11that are similar to corresponding elements of the embodiment accordingto FIG. 10 are designated with the same reference numerals. Theembodiment according to FIG. 11 does not comprise a filter above thelight sensor 4. The optional UV IR blocking filter is recessed above thelight sensor 4.

Further embodiments can be derived from the variety of embodimentsaccording to FIGS. 1 to 11. The array of sensor elements 3 may beprovided with filter elements 11, 12, 13 or further sensor elements 3′.The molding material 36 with or without optical isolation 37 or diffusor38, the filter layer 10, the UV IR blocking filter 14, the furtherfilter 48, the metal spacers 22, the optical confinement 23, the opticalcomponent 24, the vias 19, 29, 39 and the lens 15 or array of lenses 15,in particular the lens 15 or array of lenses 15 above the light sensor4, are optional and may be combined in various ways to obtain furtherembodiments.

FIG. 12 is a top view of an arrangement of sensors. The array of sensorelements 3 may especially be provided with filter elements 11, 12, 13according to the pattern shown in FIG. 12. The limits between pixels areindicated with the broken vertical and horizontal lines. The differenttypes of hatching correspond to filter elements for red, green and blue,vertical parallel lines indicating green filters. Some positions of vias19 are schematically indicated by way of example. The vias 19 may bearranged all around and below the sensor elements and the lightsensor(s) 4, as schematically indicated in FIG. 12 by triple dots. Thevias 19 are favorable for providing stability by bumping. The lightsensor 4 may be a color sensor 26, for instance. FIG. 12 shows colorsensors 26 for red, green and blue. A light source 27 and/or aphotosensor 28 may additionally be provided for various applications andpurposes, including a time-of-flight sensor, for instance.

A method of producing an embodiment of the system-on-chip cameracomprising interference filters will be described in the following inconjunction with FIGS. 13 to 23, which show cross sections ofintermediate products.

FIG. 13 shows a cross section of an arrangement of the semiconductorbody 1 and the sensor substrate 2 including sensor elements 3 and alight sensor 4. The semiconductor body 1 and the sensor substrate 2 arefastened to one another, especially bonded by the intermediatedielectric layer 6. A first filter layer 31, which yields filterelements of a first type 11, is arranged on the sensor substrate 2. Afirst mask 41 is applied on the first filter layer 31 and covers theareas where filter elements of the first type 11 are to be formed. Thefilter elements of the first type 11 may be red filters, for instance,especially interference filters forming band-pass filters for red.

FIG. 14 is a cross section according to FIG. 13 after filter elements ofthe first type 11 are formed. The first filter layer 31 shown in FIG. 13is structured, especially etched, using the first mask 41 to form thefilter elements of the first type 11. Then the surface is planarizedwith a suitable material, which may be the material that is provided forthe front dielectric layer 5, in particular an oxide of thesemiconductor material of the sensor substrate 2 like SiO₂, forinstance.

FIG. 15 is a cross section according to FIG. 14 after a first furthermask 49 is applied on the planarized surface. The first further mask 49may be a photoresist layer, for instance. It has openings 50 in areasadjacent to the filter elements of the first type 11.

FIG. 16 is a cross section according to FIG. 15 after trenches 51 areetched in the planarized surface. The trenches 51 are etched through theopenings 50 of the first further mask 49 into the front dielectric layer5. The trenches 51 can be formed by dry etching, for example. The firstfurther mask 49 is subsequently removed.

FIG. 17 is a cross section according to FIG. 16 after the trenches 51are filled with an optically shielding material, which may especially bea metal like tungsten or TiN, for instance. The trenches 51 can befilled by deposition, in particular chemical vapor deposition. A planarsurface is obtained by subsequent chemical mechanical polishing orisotropic backetch, for example. Thus the spacers 22 are formed toprovide apertures limiting the solid angle of incidence.

The spacers 22 can instead be formed as sidewall spacers before thefront dielectric layer 5 is applied. Spacers can be formed by aconformal deposition of the material that is provided for the spacers 22and subsequent anisotropic etching.

FIG. 18 is a cross section according to FIG. 17 after a second filterlayer 32 is arranged on the planarized surface. The second filter layer32 yields filter elements of a second type 12. A second mask 42 isapplied on the second filter layer 32 and covers the areas where filterelements of the second type 12 are to be formed. The filter elements ofthe second type 12 may be green filters, for instance, especiallyinterference filters forming band-pass filters for green. In the exampleshown in FIG. 18, the second mask 42 comprises a further portion abovethe light sensor 4. Thus a suitable filter layer, which is a greenfilter in this example, can be formed above the light sensor 4 togetherwith filter elements that are provided for the array of sensor elements3.

FIG. 19 is a cross section according to FIG. 18 after filter elements ofthe second type 12 are formed. The second filter layer 32 shown in FIG.18 is structured, especially etched, using the second mask 42 to formthe filter elements of the second type 12. Then the surface isplanarized with a suitable material, which may again be the materialthat is provided for the front dielectric layer 5, in particular SiO₂,for instance. Further metal spacers 22 can be applied to the filterelements of the second type 12 according to the above description.

FIG. 20 is a cross section according to FIG. 19 after the spacers 22 areformed in the layer of the filter elements of the second type 12 and athird filter layer 33 is arranged on the planarized surface. The thirdfilter layer 33 yields filter elements of a third type 13. A third mask43 is applied on the third filter layer 33 and covers areas where filterelements of the third type 13 are to be formed. The filter elements ofthe third type 13 may be blue filters, for instance, especiallyinterference filters forming band-pass filters for blue. The order inwhich the filter layers 31, 32, 33 for the different types of filterelements 11, 12, 13 are applied may differ from the example given above.

FIG. 21 is a cross section according to FIG. 20 after filter elements ofthe third type 13 are formed and the surface is planarized. The thirdfilter layer 33 shown in FIG. 20 is structured, especially etched, usingthe third mask 43 to form the filter elements of the third type 13. Thenthe surface is planarized with a suitable material, which may again bethe material that is provided for the front dielectric layer 5, inparticular SiO₂, for instance. Further metal spacers 22 can be appliedto the filter elements of the third type 13 according to the abovedescription.

FIG. 22 is a cross section according to FIG. 21 and further shows a UVIR blocking filter layer 34, which may be arranged on the planarizedsurface if a UV IR blocking filter 14 is desired. The UV IR blockingfilter layer 34 may comprise a sequence of layers as schematicallyindicated in FIG. 22. The UV IR blocking filter layer 34 may bemaintained as an entire layer, or it may be structured using a fourthmask 44.

FIG. 23 is a cross section according to FIG. 22 after an optional fourthmask 44 is applied. The fourth mask 44 is used to structure the UV IRblocking filter layer 34, so that the UV IR blocking filter 14 isproduced, which may be accomplished by etching. Recesses thus formed inthe UV IR blocking filter layer 34 are filled with suitable material,which may again be the material that is provided for the frontdielectric layer 5, in particular SiO₂, for instance.

FIG. 24 is a cross section according to FIG. 23 after an optional lenslayer 35 is arranged on the planarized surface. The lens layer 35 mayespecially be an oxide of the semiconductor material of the sensorsubstrate 2, in particular SiO₂, for instance. A transfer mask 45 isapplied, which has the shape of the lens 15 or array of lenses 15 thatis to be formed. The transfer mask 45 may be a structured and annealedresist layer, for instance. The shape of the transfer mask 45 istransferred to the lens layer 35, in particular by etching. Thistechnique of transferring a surface structure of an upper layer to alower layer is known per se. The use of a lens layer and a transfer maskis only one way of producing a lens or array of lenses. The method isnot restricted to this variant, and any other conventional method can beemployed to produce a lens or array of lenses.

FIG. 25 is a cross section according to FIG. 24 after the lens 15 orarray of lenses 15 is formed. The transfer mask 45 is completely removedduring or after the etching process. In the example shown in FIG. 25,the lens layer 35 has been removed from all areas outside the areaoccupied by the lens 15 or array of lenses 15. Instead, portions of thelens layer 35 may remain in an area that is not occupied by the lens 15or array of lenses 15, as in the embodiments according to FIGS. 7, 8, 9,10 and 11.

FIG. 26 is a cross section according to FIG. 25 after the formation ofvia holes in the semiconductor body 1. The via hole 19 is provided foran electric interconnection through the semiconductor body 1. An opticalvia 39 may be provided for a further optical component. It may besuitable if the sensor substrate 2 is recessed above the optical via 39as shown in FIG. 26.

FIG. 27 is a cross section according to FIG. 26 after the application ofa metallization 21 for the electric interconnection through thesemiconductor body 1 and the arrangement of an optical component 24 onthe rear side of the semiconductor body 1. The embodiment according toFIG. 3 can then be obtained by further method steps including theapplication of a molding material.

The described system-on-chip camera allows to enhance the integration ofoptical components such as filters and lenses at wafer level andespecially to reduce the size of the camera. Furthermore it facilitatesthe integration of multiple CMOS image sensors with discrete sensorssuch as ambient light sensors, color sensors and/or time-of-flightsensors, for example.

We claim:
 1. A system-on-chip camera, comprising: a sensor substratecomprising semiconductor material; sensor elements arranged in thesensor substrate according to an array of pixels; a light sensor in thesensor substrate apart from the sensor elements; and a surface ofincidence above the sensor elements and the light sensor; a lens or anarray of lenses formed by an oxide of semiconductor material arranged onthe surface of incidence; a molding material covering the lens or arrayof lenses; a diffusor formed above the light sensor by a modified regionof the molding material; the sensor substrate being connected to asemiconductor body comprising an integrated circuit, and the sensorsubstrate being arranged between the semiconductor body and the surfaceof incidence; and each of the sensor elements being provided with afurther component arranged between a respective sensor element and thesurface of incidence, the further component being a stack of furthersensor elements arranged in the sensor substrate and providing adifferent spectral sensitivity than the sensor elements, and the sensorelements and the further sensor elements being arranged at differentdistances from the surface of incidence.
 2. The system-on-chip cameraaccording to claim 1, further comprising: metal spacers laterallyarranged at the further sensor elements.
 3. The system-on-chip cameraaccording to claim 1, further comprising: a filter layer arrangedbetween the light sensor and the surface of incidence, the filter layerbeing a band-pass filter for either red, green or blue light.
 4. Thesystem-on-chip camera according to claim 1, further comprising: ametallization layer between the semiconductor body and the sensorsubstrate; a contact pad, the semiconductor body being arranged betweenthe metallization layer and the contact pad; a via hole in thesemiconductor body; and a metallization in the via hole, themetallization electrically connecting the metallization layer and thecontact pad.
 5. The system-on-chip camera according to claim 1, furthercomprising: a metallization layer between the semiconductor body and thesensor substrate; an optical component above the surface of incidence;and a through-substrate interconnection electrically connecting themetallization layer and the optical component.
 6. The system-on-chipcamera according to claim 1, further comprising: an optical viapenetrating the semiconductor body, and an optical component oppositethe optical via on a side facing away from the sensor substrate.
 7. Thesystem-on-chip camera according to claim 1, wherein the light sensor isa sensor selected from the group consisting of an ambient light sensor,a color sensor, a hyperspectral sensor with multiple pixels or bands, aninfrared sensor and a UV sensor.
 8. The system-on-chip camera accordingto claim 1, further comprising: a proximity sensor, a gesture sensor ora time-of-flight sensor including a light source.
 9. The system-on-chipcamera according to claim 1, wherein the light sensor comprises an arrayof light sensors serving as a further camera.
 10. A method of producinga system-on-chip camera, comprising: providing a semiconductor body withan integrated circuit; providing a sensor substrate with sensorelements, the sensor elements forming an array of pixels, and with alight sensor apart from the sensor elements such that a surface ofincidence is above the sensor elements and the light sensor; providing afurther component arranged between each of the sensor element and thesurface of incidence, the further component being a stack of furthersensor elements arranged in the sensor substrate, wherein the sensorelements and the further sensor elements are arranged at differentrespective distances from the surface of incidence and wherein thesensor elements provide a different spectral sensitivity than thefurther sensor elements; fastening the sensor substrate to thesemiconductor body such that the sensor substrate is arranged betweenthe semiconductor body and the surface of incidence; and arranging alens or an array of lenses formed by an oxide of semiconductor materialon the surface of incidence above the sensor substrate; applying amolding material covering the lens or array of lenses; and forming adiffusor above the light sensor by modifying the molding material in aregion above the light sensor.